Effective tissue procurement and utilization is vital for meaningful translational research activities. The Pathology and Tissue Core will work with each SPORE project and the Biostatistics and Data Management Core to ensure efficient and highly coordinated procurement, use and storage of blood and bone marrow samples. The Core will obtain and maintain a repository of blood samples (including peripheral blood, bone marrow biopsies, and bone marrow aspirates) for laboratory use, with an effective coding system for all laboratory specimens to ensure patient confidentiality and prevent experimental bias. Continuous communication between the investigators, research nurses, biostatisticians and hematopathologists, as well as standardized operating procedures for activities will provide for optimal tissue collection and accurate processing, analysis and storage of each sample. Thus, the functions of the Pathology and Tissue Core are to facilitate acquisition, preservation, analysis and dispersal of clinical samples and to provide hematopathologic characterization and specimens for all project investigators. The Tissue Procurement and Hematopathology Core has the following objectives: * Develop and maintain a repository of blood and bone marrow specimens, including intact cells, serum, cellular DNA, RNA and protein, from patients with leukemia and MDS (including patients who are newly diagnosed, in remission or in relapse) receiving care or evaluation at M.D. Anderson Cancer Center. Distribute tissue specimens to SPORE investigators for analysis and provide expertise in the interpretation of studies performed on tissue sections within SPORE projects Provide comprehensive histologic characterization of blood and marrow samples used in SPORE projects, including specimens from patients entered onto clinical protocols. * Maintain a comprehensive, prospective interactive database with detailed clinical and pathologic data for patients with leukemia and MDS receiving care or evaluation at M.D. Anderson Cancer Center * Facilitate inter-SPORE collaborations through sharing of blood and marrow resources